Further work is proposed toward the development of an implantable prosthesis to replace the urinary bladder after cystectomy and thus eliminate the need for surgical construction of alternte routes to void urine. The prosthetic bladder empties without use of external or transcutaneous energy, hence the term "passive". Functional efficiency of passive voiding and other prosthetic functions was shown in preliminary implantations. The bladder prosthesis includes ureters with anti-reflux valves, a bladder region for urine storage and a urethra with valve and associated subcutaneious actuator: accordingly, the device that is being developed is a total prosthetic bladder. Urine compatibility will be provided by forming all surfaces that contact urine from a hydrogel, poly(2-hydroxyethyl methacrylate), pHEMA. Through 3-year-implantation tests, we have shown the urine compatibility of prosthetic ureters of tubular, bulk pHEMA. Most surfaces of the prosthesis will have a chemically grafted coating of pHEMA; grafting uses a cerium-ion technique developed to make blood-compatible surfaces. Prosthetic ureters with grafted pHEMA surfaces will be implanted to insure that grafted pHEMA has the same compatibility as previously studies bulk pHEMA. Work over the past year improved fabrication methods for polyurethane structures, extended the protocol for grafting pHEMA to complex geometries, and performed accelerated cyclical tests that show the total bladder prosthesis has an expected lifetime greater than 3 years. Cyclical testing was ended to allow surface examination, which showed no damage to the grafted pHEMA. Proposed work includes optimization of fabrication methods, comprehensive quantitative studies of reliability, fatigue, and wear of pHEMA surfaces and total bladders, in vivo studies of prosthetic ureters with grafted pHEMA surfaces, in vivo studies of encapsulation of balloons whose shape and motion mimic the prosthetic bladder, and short-term studies of total prosthetic bladders. The aim of the three-year period of work is to produce a prosthesis that is ready for long-term(3-year) animal tests of urine and prosthesis compatibility.